


Infidelity

by rainandhotchocolate



Category: Harry Potter - J. K. Rowling
Genre: Consensual Infidelity, F/M, Infidelity
Language: English
Status: Completed
Published: 2019-10-01
Updated: 2019-10-01
Packaged: 2020-11-09 03:51:24
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,905
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20847089
Author URL: https://archiveofourown.org/users/rainandhotchocolate/pseuds/rainandhotchocolate
Summary: Lily knew it was wrong, being with her boyfriends best friend, but every time they were alone together she couldn't help but find somewhere more private for them to go...





	Infidelity

**Title:Secrets**  
**Author: Rainandhotchocolate**  
**Pairing(s)/Character(s): Sirius/Lily **  
**Rating: 18+**  
**Word Count: 1.8k**  
**Prompt #: They know it’s wrong but they can’t stop.**  
**Content/Spoiler:** Highlight to read *ADD TEXT HERE*   
**Disclaimer: ** Harry Potter characters are the property of J.K. Rowling and Bloomsbury/Scholastic. No profit is being made, and no copyright infringement is intended.  
**Notes: Mentions of infidelity :**  
**Summary: Sirius and Lily can’t seem to stop spending time together, alone, without any clothes on. **

Lily felt her back get pushed up against a stack of brooms that dug a little painfully into her shoulder blades, but she ignored it, instead watching the wild grey eyes that were staring back at her.

“Fuck,” Sirius swore under his breath before he closed the small distance between them and kissed her, hard. She moaned into his mouth, desperate to taste him again, feeling her stomach flip over at his touch, the memories of how good it felt last time overriding any part of her brain that was screaming at her to stop.

“Sirius!” She gasped suddenly as he bit down on her collarbone, “He’s going to notice that.”

He growled at her words but sucked lighter, moving up towards her neck, peppering kisses along to her ear. He tucked a long strand of red hair behind it before lightly sucking on the lobe, grinning as she moaned louder, bending her neck back onto the wall. 

“This seriously has to be the last time,” Lily muttered, breathing heavily as he pulled a hand through her hair before pulling it backwards. 

“Better make it count then,” Sirius paused momentarily to look at her, flushed cheeks and green eyes staring intensely into his own.

He hadn’t meant for this to happen, obviously. James was his best friend, his brother. The first time it even happened was before James and Lily ever got together, a drunken night after a terrible Gryffindor loss to Ravenclaw. James had resided to his bedroom to avoid everyone and hide underneath the covers, and Lily had decided that with James not around to watch her every move she might try a drink… or seven. 

They had both ended up outside the common room portrait hole to get some fresh air. And then they were in a classroom and Lily was pushing him up against the back wall and guiding his fingers inside of her. Sirius remembered how hot he found her, taking control, and how unbelievable it felt to hitch up her skirt and push himself inside of her, her pale breasts poking out from her half-unbuttoned school shirt heaving in time with his hips. 

It hadn’t meant to continue once James and Lily officially got together, but every time they ended up alone together Lily could feel herself get wet at just the thought of Sirius whispering in her ear, body pressed up against hers. There was something so much hotter about the secrecy of it all, Sirius holding his hand across her mouth as he fucked her in the shower to stop her screaming his name, Lily sitting on top of him outside the Potter house, grinding on top of him until he came loudly, her red hair swinging across her breasts. 

Sirius slowly unbuttoned her blouse, watching her chest breathe in and out as he revealed her pink lacy bra, biting his lip when he thought of her wearing that just for him, the lace just covering her nipples. He pulled off the shirt, kissing slowly down her breasts as she watched him carefully, wanting him to grab them, but not wanting to interrupt him teasing her. Finally, he unhooked the bra and bit down on each nipple in turn, sucking lightly until she moaned again, Lily grabbing his shirt and pulling him in closer so she could pull it up and over her head.

Not a second before it was of him he lifted her up, hooking her legs around his waist by grabbing his hand around her ass and pushing her harder against the wall so she was supported and could admire the bulking muscle in his arms that were gripping her just tight enough that her muscles tensed. 

There was something about Sirius, the intensity with which he watched her every time she moaned, wanting to see every inch of her shake because of him, his eyes full of lust. It was the way he let himself lose control completely whenever he was with her, Lily couldn’t help but want to feel that powerful, that she could make Sirius Black lose control.   
He pressed his hips hard up against her so he could quickly flick off his belt and slip off his trousers, revealing his large, throbbing penis. She felt her mouth water a little, itching to touch it, and it was like he read her mind. He placed his hands back on her ass and pulled at her underwear, lifting her up quickly so she could help get them off her, leaving her naked except for her skirt. 

Lily had learnt quickly that Sirius had a bit of a kink for leaving things half on, the temptation of something, it was probably how they ended up together in the first place, Lily was the definition of something forbidden. 

He slid his hands underneath her skirt so that he could feel her completely bare for him, sliding his nails across her skin and leading one hand towards her vagina, beginning to slide it up and down the very tip of her clitoris, waiting for her to beg. 

Lily hated sometimes how much he knew her, how he knew all the places to touch her to make her putty in his hands, and before long Lily was pulling back his hair roughly, begging for him to make her cum. 

“As you wish,” he grinned, lifting her up higher so that her legs were now wrapped tightly around his neck and his face was at the perfect angle to start flicking his tongue along the vulva. Lily moaned loudly, grabbing onto one of the broom hooks behind her as he slowly built speed across her clitoris. 

Suddenly he licked the length of her clitoris, sucking on it lightly, before returning to lightly flicking his tongue back and forth along it. He felt his penis twitch at the sound of her gasp and buck into his face, begging for more of him, begging for him to make her scream. Lily felt her head bang up against the wooden cupboard walls as felt wave after wave of small pleasures building into her stomach. 

Sirius felt Lily’s legs around him begin to shake and placed a finger around the entrance to her vagina, grinning into her as Lily’s eyes rolled into the back of her head and she slid her nails across the top of his skull, desperate to grab anything of his, now just saying his name over and over again. 

Lily felt him push his index finger into her and bucked again, overcome with wanting to feel more of him, more touching, more of him inside her. She could feel herself coming close to the edge, concentrating on his tongue moving expertly between her legs as her back began to arch from underneath her and her whole body started shaking uncontrollably. 

“Fuck, Sirius, please keep going, please, I want you so bad” She rolled her head back and she felt him moan into her. He reached up and grabbed one of her breasts, rubbing a thumb over her nipples until she came, screaming his name across the dorm, scrunching her hands into fists and squirming, her legs shaking. 

Sirius dropped her down from his shoulders, but kept her tight against him, wrapping her legs back around his waist. 

“Looking for more, are you?” Lily heaved a breath, watching him with her head cocked to one side. He licked his lips, moving a finger softly over her nipples so she felt little jolts of electricity run through her. She began to hear movement outside, it was lunchtime, and they had spent their free period holed up together in the very cosy cupboard. She could tell that Sirius was thinking the same thing as herself, would James notice they were both gone? 

But Lily could also feel Sirius penis pressed up against her, so dangerously close to the entrance to her vagina that she felt physically frustrated and she made the decision for them, angling her hips towards him and using her legs to pull his penis into her. They both moaned, loudly, Sirius quickly clamping a hand over Lily’s mouth to stop any noise from seeping into the hallways, and began to fuck her slowly and deeply so that they could both feel every single inch move in and out. 

Sirius picked up his belt and swiftly looped it around the hook that Lily had grabbed onto earlier and tightened them together, both lifting Lily up lightly and making her heart race at the idea of being tied up and stuck there with him. He grinned at her and dropped his hand around her mouth, indicating to keep quiet before pushing himself harder into her.   
Lily felt a moan stop short in her throat as she desperately tried to avoid making any noise, Sirius continuing to fuck her hard, making sure to kiss down her chest as he did so. Lily felt her head hit the back of the cupboard again but didn’t care one bit, relishing the feeling of having him move up and down and up and down inside of her, wanting to be closer to him somehow, wanting to wrap every part of herself in him. 

“I want more, please” She begged, rocking into him. Sirius, watched momentarily as her breasts moved up and down above him before speeding up, watching her breathing hitch and her teeth bite hard onto her lip to stop herself from screaming (what he hoped) would have been his name. He grabbed her arm roughly, trying to hold off from finishing before her. Y/N moaned again, bucking her hips up as she felt every inch of him push up and into her.

“Fuck, Lily” Sirius finally gripped her waist and pushed hard into her one more time as he came, pressing his forehead up against her stomach. Lily pulled herself away from him, pulling on her underwear from the floor beside her. They dressed in silence, they had a routine in place, a way to get themselves ready for the outside world in under a minute.   
They stood, watching each other for a couple of seconds before Sirius took a deep breath and put one hand on the doorknob, letting Lily know that he’s about to open the door. She prepared herself, flattening her hair one more time and Sirius opened the door, hiding behind it so she could step out and check for anyone in close range.

“Coast is clear,” Lily murmured, stepping out into the seventh-floor corridor and Sirius followed her, closing the door behind her. 

“Lunch?” Lily cleared her throat, trying to put herself back into friend-mode, James’ long-term girlfriend mode. 

“Lunch,” Sirius nodded his head and pushed passed Lily to lead the way down to the Great Hall, grabbing her ass quickly on the way past. 

“Shit” Lily swore, closing her eyes for a second and hurrying after him. This definitely isn’t going to be the last time.


End file.
